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Pentagon official: FCC decision on 5G threatens GPS, national security

thehill.com

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Re: Pentagon official: FCC decision on 5G threatens GPS, national security

#131

Post by duskwuff »

michaelt wrote: post #113
josh2600 wrote: post #46

Earlier quoted context omitted.

When light squared was shut down for messing with gps frequencies in their satellite network, the military did not say that light^2 was actually broadcasting outside of the expected frequency band. The deal is that the military just doesn’t use filters on most of their broadcast and reception equipment so their operating frequency is actually way wider than they say publicly. This is because filters cost money and re…

> The deal is that the military just doesn’t use filters Do you have a citation for that? I would have thought the issue is not that GPS receivers don't use filters, but rather than no filter has a perfectly sharp cut-off and GPS signals are exceptionally faint. For example, if the GPS signal is 0.1 femtowatts at 1575MHz, even if you've got a filter that can remove 99.99999% of a noise signal at 1600MHz you can still…

Precisely -- no RF filter has a perfect "brick wall" response, and no transmitter will have a perfectly pure output either. GPS receivers already have to use some pretty crazy tricks to pull a signal out of the noise; it doesn't take a lot of interference to make that impossible.

Re: Pentagon official: FCC decision on 5G threatens GPS, national security

#132

Post by Junk_Collector »

takeda wrote: post #107
oblio wrote: post #75

Earlier quoted context omitted.

There are 2 kinds of 5G, millimeter wave and non millimeter wave. The one you are talking about is millimeter wave 5G. The other one has pretty long range, goes through building, doesn't use up that much more battery and is overall a better technology (higher bandwidth, better congestion control and overall capacity for more connections in a crowded area, lower latency, etc.).

The 5G is pitched because greater speeds, and correct me if I'm wrong, but the millimeter waves are the reason for higher bandwidth otherwise it is similar to 4G that can peak to 1Gbps.

FR1 (the low band 5G) is capable of greater carrier aggregation and denser QAM modulation than LTE-A so it can achieve higher bandwidths than LTE-A under good conditions. It also has better latency and congestion controls which should provide a better general use experience as well as reduce degradation in heavy traffic. It also pushes more open hardware/software standards for base stations to reduce vendor lock-in.

Re: Pentagon official: FCC decision on 5G threatens GPS, national security

#133

Post by duskwuff »

sasasassy wrote: post #91
neltnerb wrote: post #11

Earlier quoted context omitted.

I'm a little worried that GPS is so vulnerable that these satellites could cause such disruption to be honest. This is satellite based, any country could be approving this plan and the impact on GPS would still be present since orbits go everywhere. I guess I'd rather they just... not... I don't really even think the trade-off in increased seemingly real health risk is worth making the cell network even faster. It's…

Let me just point out that satellites don't necessarily orbit around the world. They can be geostationary, and in fact they usually are I think. That is why you will find most US GPS satellites over the US, most Russian satellites over Russia, etc. Also, signal disruption is already very common as a necessary precaution at sensitive times and places. I think many military bases and other sensitive places, like the Kr…

GNSS satellites (GPS, Galileo, GLONASS, Beidou, etc) are not in geostationary orbits. Being in a geostationary orbit would put them in fixed "locations" in the sky, making them easily blocked by terrain and entirely unusable at high latitudes.

GPS satellites are in MEO, at ~20 km MSL. Other GNSS satellites use similar orbits.

Re: Pentagon official: FCC decision on 5G threatens GPS, national security

#134

Post by duskwuff »

grawprog wrote: post #76
Junk_Collector wrote: post #58

Earlier quoted context omitted.

The counter 5G bandwagon seems to be largely comprised of conspiracy theories, dubious health claims, and unqualified assertions that people don't want more bandwidth. Why would you poison a legitimately important topic like spectrum allocation with associations like that?

Personally, I dislike how the conspiracy nonsense has kind of covered up the actual criticisms of 5g that existed prior to suddenly everyone thinking it's a great idea and if you don't, you're a conspiracy theorist. I seem to recall this revolved around, questionable tangible benefits vs cost of deployment, poor penetration of 5g signals through structures, a lack of devices or internet plans to take advantage of 5g,…

One has to wonder if some of the nonsense criticisms of 5G (causes disease, government conspiracy, etc) have been deliberately amplified to drown out legitimate technical concerns.

Re: Pentagon official: FCC decision on 5G threatens GPS, national security

#135

Post by Rebelgecko »

jrockway wrote: post #38

I don't think there's enough detail here to decide whether or not to be mad. The L band is huge, 1000MHz-2000MHz. GPS uses a few tiny slices of this band. Cell phones, amateur radio, weather radar (though not precipitation-detection radar), ADS-B, and a ton of other non-military things are in that band. Adding 5G may or may not have any negative effect on GPS. I doubt they are proposing to run their 5G network on top…

I'm not an RF person, but the way it was explained to me is that GNSS signals are in the neighborhood of 1560mhz-1610mhz. With the advent of GPSIII, even more of the important signals are getting pushed outwards towards the extremes of that range. Ligado/Lightsquared initially wanted permission to basically surround GPS (1526-1559mhz and 1610-1660mHz)

After lots of complaints, they amended their request to leave a buffer of 20mhz or so between their signals and GPS. However, Ligado wants to transmit at ~10watts, and the GPS signal is in the neighborhood of a femtowatt by the time it hits a receiver. That can apparently still cause interference. For the GPS chip in your phone it may not make a huge difference. However testing has shown degraded performance in aviation GPS receivers more than a mile away from a 10watt transmitter. For even higher precision receivers (think surveyor equipment or maybe an autonomous tractor) the radius of the degradation stretches more than 2 miles from the transmitter. Ligado wants to put their transmitters ¼ of a mile apart.

Source for some of those numbers here, and an entertaining talk if you're ever able to see it in person: https://rntfnd.org/wp-content/uploads/Brad-at-UAG-Users-Advi...

Re: Pentagon official: FCC decision on 5G threatens GPS, national security

#136

Post by Rebelgecko »

dwater wrote: post #109
_bxg1 wrote: post #45

I have yet to hear anyone who's not a telecom CEO or a politician say they actually want 5G

I've heard that top brass at the DoD is fixated on 5G being critical to military superiority in the near future, without really having any practical understanding of its strengths and weaknesses or real world applications. But it's become a hot buzzword and an easy way to drum up money and attention. The fact that China is a major player is also helping funnel funding into many money-torching projects.

All of the statements I've seen from pentagon brass are extremely critical of the FCC's decisions to let 5G operate close to bands used for GPS and weather forecasting.

Re: Pentagon official: FCC decision on 5G threatens GPS, national security

#137

Post by Rebelgecko »

_bxg1 wrote: post #45

I have yet to hear anyone who's not a telecom CEO or a politician say they actually want 5G

I'd like to have an alternative to the ISP monopoly that exists at my address (technically I have 2 options, but one of them is about 30x faster than the other for the same price)

Re: Pentagon official: FCC decision on 5G threatens GPS, national security

#138

Post by [deleted] »

omneity wrote: post #128
_bxg1 wrote: post #59

Earlier quoted context omitted.

Except: - It's shorter-range, so coverage will be spotty for a long time - It doesn't go through buildings , so even the urban centers most likely to get the first towers will have spotty coverage - It will require buying a new device, which OEMs love but the average person won't - That device will take a hit in battery life And all of this for ludicrously-fast new speeds on mobile devices that we'll use for... what…

> What experience is 5G, assuming you actually have access to it, going to improve? Remotely operated robotics due to the much lower latency. Think near instant reaction times while operating a drone with VR goggles, and all the implication this could have. Also many other use cases become more feasible: - Self driving cars with human fallbacks - Safer car racing - Actually smart delivery, where a single person can m…

[deleted]

Re: Pentagon official: FCC decision on 5G threatens GPS, national security

#139

Post by Rebelgecko »

sasasassy wrote: post #91
neltnerb wrote: post #11

Earlier quoted context omitted.

I'm a little worried that GPS is so vulnerable that these satellites could cause such disruption to be honest. This is satellite based, any country could be approving this plan and the impact on GPS would still be present since orbits go everywhere. I guess I'd rather they just... not... I don't really even think the trade-off in increased seemingly real health risk is worth making the cell network even faster. It's…

Let me just point out that satellites don't necessarily orbit around the world. They can be geostationary, and in fact they usually are I think. That is why you will find most US GPS satellites over the US, most Russian satellites over Russia, etc. Also, signal disruption is already very common as a necessary precaution at sensitive times and places. I think many military bases and other sensitive places, like the Kr…

GPS wouldn't really work in a geostationary orbit (there'd be no way to tell if your latitude is North or South)

Re: Pentagon official: FCC decision on 5G threatens GPS, national security

#140

Post by OrgNet »

_bxg1 wrote: post #59
sl1ck731 wrote: post #53

Earlier quoted context omitted.

I mean, I'm sure a lot of people want it if it improves their mobile experience. It isn't really something that the average person is going to celebrate on Facebook.

Except: - It's shorter-range, so coverage will be spotty for a long time - It doesn't go through buildings , so even the urban centers most likely to get the first towers will have spotty coverage - It will require buying a new device, which OEMs love but the average person won't - That device will take a hit in battery life And all of this for ludicrously-fast new speeds on mobile devices that we'll use for... what…

> - That device will take a hit in battery life

4G was a real battery drain at first

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